Underwater sound projectors have a number of uses including communication, object detection, and geographic mapping.
For example, underwater sound sources may be used to track buoys that are free floating through the ocean. Underwater sound sources may be placed 1,000 meters or more below the ocean surface and placed into the deep sound channel or SOFAR channel that provides for extremely long distance sound propagation within the ocean. The data collected from the buoys illustrates current flow across large stretches of ocean. An example of an underwater sound source is described in U.S. Pat. No. 6,814,180. The sound source described in this issued U.S. Patent uses a tubular housing with a monopole driver positioned within the housing. Sea water floods the housing and the driver causes the tubular housing to vibrate. This provides a narrow-band underwater sound source that resonates at a frequency dependent upon the geometric characteristics of the tubular housing.
Broadband underwater sound projectors have also been developed. These broadband sources can transmit in wide range, such as in the range of 10 kHz to 100 kHz. One such broadband underwater sound projector was described by Howarth and Ting in the government publication “Development of a Broadband Underwater Sound Projector,” www.matsysinc.com/products/sonar_transducers/docs/dev_broadband_underwater_sound_projector.pdf. That underwater broadband sound projector includes an enclosed conical diaphragm that vibrates for the purpose of generating a broadband acoustic sound. These systems can work well, but tend to have a fixed frequency range.
There remains a need for improved broadband underwater sound sources.